Behaviorally based techniques have been shown to produce statistically reliable blood pressure reductions in normal and hypertensive subjects. However, in spite of notable exceptions in which impressive results were obtained, most studies have failed to produced blood pressure reductions of a clinically meaningful magnitude in a large proportion of treated patients. Although these results do not justify the use of behavioral techniques as an alternate form of therapy, they do suggest that behavioral techniques may be of real value in treating hypertension. The purpose of this research is to explore the clinical value of behavioral techniques used as adjuncts to conventional pharmacotherapy. One hundred essential hypertensive patients will receive either: 1) medication only, or medication combined with, 2) progressive relaxation training, 3) instructions to relax on their own, or 4) constant-cuff diastolic blood pressure biofeedback. Blood pressures will be recorded in the laboratory, in a medical clinic, and in the patient's home on a monthly basis before, during, and for l2 months following behavioral treatment. Outcome measures will include blood pressure changes, medication requirements, anxiety levels, side effects of medications, and compliance with medical and behavioral therapies. A number of variables have also been identified which will be used as prognosticators of the response to combined pharmacologic and behavioral therapies.